Former Yale basketball captain Jack Montague filed a lawsuit Thursday accusing the Ivy League university of wrongfully expelling him over a sexual assault allegation.

The lawsuit, filed in federal court in Connecticut, says Montague was punished over what he believes was consensual sex. It says Montague had a relationship with the woman, a fellow Yale student, and asserts that she came back to his room to spend the night after the encounter in question in October 2014.

The lawsuit argues that the university used the case against Montague, a popular and well-liked athlete, as an opportunity to show it was tough on sexual misconduct following a survey on sexual assault by the Association of American Universities. The association estimated that one in four Yale undergraduates had experienced an incident that "does not meet Yale's standard for consent."

"In short, imposing harsh discipline on Montague would surely make an impact," the lawsuit says.

A Yale spokesman, Tom Conroy, said the lawsuit is factually inaccurate and baseless and the university plans a vigorous defense.

"Yale's procedures for addressing allegations of sexual misconduct are thorough and fair," he said. "Allegations are investigated by an impartial fact-finder, heard by five trained members of the Yale community, and decided by the accused student's dean."

Montague, a senior, was accused in a complaint filed on the woman's behalf by a Title IX official Nov. 18. A university panel ruled against him, and the provost upheld the ruling, according to his attorneys. Montague was expelled Feb. 10.

His lawsuit names Yale as a defendant along with two university officials who were involved in processing the complaint against him. It alleges the woman only wanted someone from the school's Title IX office to talk with Montague about the incident and provide training but she was encouraged to participate in a formal complaint process.

According to the lawsuit, the woman said in her account to a fact-finder that she told Montague she did not want to have intercourse but he looked as if he did not hear what she said. Montague told the fact-finder that nothing about the encounter made him think the woman was hesitant or uncomfortable. The dispute is about the last of four sexual encounters between the two students, his attorneys say.

Police and the local prosecutor said no criminal allegation has been filed in the case.

The lawsuit asks that Montague be reinstated as a student or for Yale to reopen the proceedings against him. It also seeks damages.

Expulsion at Yale requires a threshold of "preponderance of the evidence" for establishing wrongdoing, lower than any criminal case.

"Only about one out of 10 cases ends in expulsion, and the decision to expel a student is made only after the most careful consideration, based on the facts and, when appropriate, disciplinary history," the school said.